Structural changes in the male reproductive tract of the stingless bee Scaptotrigona xanthotricha Moure, 1950 (Meliponini, Apidae) during sexual maturation.

Abstract

Stingless bees are social insects widely distributed in the Neotropical region but their populations have declined due to loss of habitats and the increase use of pesticides in agriculture. Thus, the knowledge of the biology of these insects, including reproductive biology is important for their conservation and management. This study describes the morphological changes in the male reproductive tract during the sexual maturation in the stingless bee Scaptotrigona xanthotricha (Moure, 1950). The gross morphology and histology of the reproductive tract was investigated from pupae to 22 days old adults. The male reproductive organs in S. xanthotricha are a pair of testes, each with four follicles, pair of vasa deferentia with enlarged seminal vesicle region that open in an ejaculatory duct. In the male reproductive tract of this bee there are no is accessory glands. From brown-eyed pupae to newly-emerged adults, the epithelia of the seminal vesicle and postvesicular vasa deferentia have prismatic cells, which release secretion to the organs lumen. In 5-days old adults the testes undergo degeneration, the seminal vesicle is filled with secretion and spermatozoa, and its epithelium has cubic cells rich in inclusions in the basal region suggesting that males reach the sexual maturation. Structural modifications in the reproductive tract during sexual maturation are discussed concerning the reproductive biology of Meliponini.